It is generally accepted that snoring and obstructive sleep apnoea occur when a sleeping person's tongue fully or partially blocks a constricted airway. Lifestyle changes, such as exercise and weight loss, are helpful in improving a constricted airway by reducing fat and increasing the muscle tone of the throat. However, this approach does not resolve the condition for all sufferers. Various devices and approaches to treating these conditions have been proposed.
Devices which move the mandible (lower jaw) forward and down from its habitual position relative to a patient's upper jaw also move the tongue forward and down in the mouth, and are consequently thought to reduce the likelihood of the tongue blocking or partially blocking the airway. Such devices are known as mandibular advancement devices.
One such device, disclosed in patent application WO 00/01317 by Palmisano, has an arrangement in which an upper and a lower dental plate are attached over a patient's lower and upper jaw. The plates define engaging sloping surfaces which are oriented such that as a patient's jaw closes, the engagement of the surfaces causes a patient's mandible to be advanced away from the habitual position relative to the upper jaw as the patient closes his jaw into the appliance.
The device described in WO 00/01317 has a number of disadvantages. In order to provide the requisite strength to make the device work, the upper and lower plates cover the incisal edges of the patient's teeth to enable the device to withstand the destructive forces of the mouth. In practice, the commercially available version of the device provided by Somnomed Limited is made with at least 2.5 mm thicknesses occlusally on both arches. This is a particular problem as it inhibits the patient's bite registration from being taken according to correct measured vertical guidelines. Also, the device is generally bulky, intrusive and relatively disturbing to patient comfort and thus encourages non-compliance by the patient (as patients do not like wearing uncomfortable devices). The hard material from which the commercially available device is made is uncomfortable to wear.
Other mandibular advancement devices are disclosed in which the upper and lower plates are connected to each other by extendable connectors, for example as is described in WO 95/19746. In such the devices, the connections intrude into the patient's oral cavity causing discomfort and thus encouraging non-compliance.
It is an object of the present invention to provide a mandibular advancement device that is effective in use while being more comfortable to wear.